General procedure for the synthesis of 2,5-dibromo-4-methylimidazole from 4-methylimidazole: 4-methylimidazole (3.4 g, 40 mmol) was dissolved in tetrahydrofuran (THF, 50 mL) at room temperature. Subsequently, N-bromosuccinimide (NBS, 14 g, 80 mmol) was added to this solution. The reaction mixture was stirred for 1 hour. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography (eluent ratio: petroleum ether (PE):ethyl acetate (EA) = 2:1) to afford 2,5-dibromo-4-methylimidazole (9.6 g, 99% yield) as a white solid. Mass spectrometry (ESI-MS) analysis showed: m/z 239.0 [M + H]+.
